In injection molding, granular molding material can be fed by gravity from a hopper into a heated barrel. The granules can be slowly advanced by a screw, which can aid in melting the molding material due to frictional heat cause by shear forces within the material. The molding material can be forced into a heated chamber, where it can be melted. The melted molding material can be forced through an injector that rests against the mold such that the material can enter the mold through a gate and runner system to a mold cavity. The mold can be kept cold by circulating a heat transfer fluid through the mold walls adjacent the cavity so the molding material solidifies as the mold is filled.
The mold can have a number of important sections. Molten material, called the melt, can enter the mold through a sprue, or channel, formed in the mold, e.g., along a mold surface or through the mold section. A sprue bushing can be tightly sealed against the injector of the injection device. A channel can be called a runner. The runner can connect to the sprue. The runner can guide the melt to the part forming mold cavity. The location at which the molten material enters the part forming mold cavity is called the gate. The amount of resin required to fill the sprue, runner, and part forming mold cavity, or cavities, of a mold is sometimes known as a “shot”. Hot melt can cool as it flows to the part forming mold cavity, as it flows along and/or within the mold sections. Thermal energy removed from the melt can travel to an ancillary cooling system. An ancillary cooling system can include a fluid heat exchange circuit in thermal communication with a mold section. An ancillary cooling system can include a fluid heat exchange circuit in fluid communication with a mold section. An ancillary cooling system can include a fluid heat exchange circuit in fluid communication and thermal communication with a mold section. As the melt cools, the inner section of the melt, farther from cool mold walls, can continue to flow and fill the mold cavity. The injector can pressurize the melt to eliminate gas bubbles. The injector can force the cooling melt against the mold cavity walls. The injector pressure can be maintained while the part solidifies. The injector pressure can be increased while the part solidifies. The injector pressure can be decreased while the part solidifies.
Challenges in injection molding can arise from controlling the temperature of a mold during each phase of the process and in every area that the plastic contacts. If a mold temperature is not controlled properly then a variety of part defects can result. If a mold temperature is not uniformly controlled then a variety of part defects can result. A temperature control system for a molding operation can be complex and can be capital intensive. A temperature control system for a molding operation can have significant customization to a particular mold design. A temperature control system for a molding operation can be inefficient. Thus there is a need in the art for a mold design that can improve control of mold temperatures, improve efficiency, and can reduce capital cost.